Abstract
Ultrafast multiphoton ionization of Xe in strong extreme ultraviolet free-electron laser (FEL) fields (91 eV, 30 fs, ) has been investigated by multielectron-ion coincidence spectroscopy. The electron spectra recorded in coincidence with show characteristic features associated with two-photon absorption to the double core-hole (DCH) states and subsequent Auger decay. It is found that the pathway via the DCH states, which has eluded clear identification in previous studies, makes a large contribution to the multiple ionization, despite the long FEL pulse duration compared with the lifetime of the core-hole states.
- Received 17 December 2019
- Accepted 14 April 2020
DOI:https://doi.org/10.1103/PhysRevLett.124.193201
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